The disclosure generally relates to alkylation of dihydroxy aromatic compounds. More particularly the disclosure relates to selective mono ortho alkylation of dihydroxy aromatic compounds.
An alkylation reaction of a dihydroxy aromatic compound typically involves a vapor phase reaction of a dihydroxy aromatic compound with an alcohol using an alkylation catalyst. Such alkylated dihydroxy aromatic compounds find applications in a wide range of industries including, among others, the polymer industry, the dye industry, the photographic industry and in medical applications. They are also known for fabricating polycarbonates for use in liquid crystal displays.
Many alkylation processes for hydroxy aromatic compounds use metal oxide catalysts. Many of the alkylating catalysts produce a mixture that often contains a high proportion of dialkylated hydroxy aromatic compounds with very low selectivities towards mono alkylated hydroxy aromatic compounds. Dihydroxy aromatic compounds tend to be more reactive than hydroxy aromatic compounds thereby having an even greater tendency to generate higher alkylated and oligomeric products and making the production of mono alkylated products more difficult.
Thus, there exists an ongoing need for improvement in the process for the preparation of mono alkylated dihydroxy aromatic compounds, particularly mono ortho-alkylated dihydroxy aromatic compounds.